Data messaging in a cellular communications network

ABSTRACT

A messaging unit (16) equipped with a cellular transceiver (38) is attached to a truck trailer (12) located within a communications network (10). The messaging unit (16) generates a data message in response to the occurrence of a reporting event. Upon generation of a data message, the cellular transceiver (38) transmits the data message over the network (10) via voice or data channels. The data message is received at an MTSO (20) and then routed to a platform (24), a clearinghouse (22), or the platform (24) through the clearinghouse (22). The data message stored at the platform (24) or the clearinghouse (22) is accessed by a host (26). A data message may be sent over a voice channel of the network (10) subject to a handshake protocol between the messaging unit (16) and the platform (24). Data messages may also be sent over a data channel of the network (10) by altering the mobile identification number (MIN) or electronic serial number (ESN) of the cellular transceiver (38). Furthermore, data messages may be sent over a data channel of the network (10) by issuing a feature request with appended data digits.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 08/175,256, filed Dec. 28, 1993, entitled "DataMessaging in a Communications Network," by William C. Kennedy III andKenneth R. Westerlage, now pending, which is a continuation-in-partapplication of U.S. patent application Ser. No. 08/095,166, entitled"Method and Apparatus for a Nation-Wide Cellular Telephone Network,"filed on Jul. 20, 1993 by William C. Kennedy III and Kenneth R.Westerlage, which is a continuation-in-part application of U.S. patentapplication Ser. No. 07/826,521, entitled "Phantom Mobile IdentificationNumber Method and Apparatus," filed Jan. 27, 1992 by William C. KennedyIII and Robert J. Charles, now abandoned.

TECHNICAL FIELD OF THE INVENTION

This invention relates generally to the field of telecommunications, andmore particularly to data messaging in a communications network.

BACKGROUND OF THE INVENTION

The proliferation of sophisticated communications systems has resultedin developments in mobile communications and in particular mobile datamessaging. Data messaging collectively refers to the transfer ofinformation over voice or data channels of a communications network. Oneapplication of data messaging is the monitoring of a group of items bycausing the items to send data messages to a remote location in responseto a recognized reporting event. For example, a truck trailer monitoringsystem may use data messaging to collect information on the currentposition and status of a fleet of truck trailers.

A network of cellular telephone systems is a suitable conduit for suchdata messaging, especially if the monitored items are mobile, such aspeople, vehicles, or cargo containers. However, the cost of usingtraditional cellular communication is prohibitive, both in terms ofchargeable air time and roamer fees.

Another problem with using traditional cellular networks for datamessaging is that the fragmentation of cellular service providersresults in disintegrated monitoring and control of cellular air traffic,which often contributes to fraudulent use of the cellular telephonenetwork. Increasing incidents of roamer fraud adds significantly to thecost of cellular air time, especially for nation-wide users of thecellular telephone network. To combat these problems, cellular serviceproviders are implementing authorization and verification procedures forvalidating roaming customers.

Therefore, a need has arisen for a communications network that handles ahigh volume of data messaging by exploiting the functionality ofexisting cellular telecommunications equipment, while reducingopportunities for fraud. In particular, a need has arisen for datamessaging to monitor the position and status of a national fleet oftruck trailers in the most cost effective and reliable manner.

SUMMARY OF THE INVENTION

In accordance with the teachings of the invention, a method andapparatus for data messaging in a communications network is providedwhich substantially eliminate or reduce disadvantages and problemsassociated with prior art data messaging systems. Furthermore, datamessaging in a cellular telephone network to monitor the location andstatus information of a fleet of truck trailers substantially eliminatesor reduces disadvantages and problems associated with prior art trucktrailer monitoring systems.

In accordance with one aspect of the invention, a system forcommunicating data messages over a cellular telephone network contains aplurality of messaging units. Each messaging unit includes a processorthat generates a data message upon the occurrence of a reporting event.Each messaging unit also contains a cellular transmitter that transmitsthe data message over the cellular telephone network. A platform coupledto the cellular telephone network receives data messages transmitted bythe messaging units and stores the data messages in a storage device. Ahost coupled to the platform accesses data messages stored by theplatform.

In accordance with another aspect of the invention, a messaging unitattached to a mobile item to be monitored sends data messages over adata channel of a cellular telephone network. The messaging unitincludes a sensor located on the mobile item that generates informationon the mobile item. A processor is coupled to the sensor and receivesthe information from the sensor. The processor generates a data messagecontaining the information upon the occurrence of a reporting event. Acellular transmitter coupled to the processor transmits the data messageover a data channel of the cellular telephone network.

In accordance with another aspect of the invention, a method for datamessaging over a cellular telephone network encodes an identifier of thecellular transmitter. Data messaging is initiated upon the occurrence ofa reporting event. The identifier of the cellular transmitter is encodedwith information on the reporting event. The encoded identifier is thentransmitted through the cellular telephone network using the cellulartransmitter and received at a remote location.

In accordance with another aspect of the invention, a method for datamessaging over a cellular telephone network issues a feature request.Data messaging is initiated upon the occurrence of a reporting event. Afeature request is then generated and data digits representinginformation on the reporting event are appended to the feature request.The feature request and data digits are then transmitted through thecellular telephone network and received at a remote location.

An important technical advantage of the invention is that data messagessent to or received from the messaging units over a voice channel of acellular telephone network are subject to a verification procedure,thereby allowing for multiple levels of fraud protection. In particular,a handshake protocol is required when a data message is directed to orreceived from one of the messaging units, thereby preventing theft ofcellular air time through roamer fraud.

Another important advantage of the invention is that messaging units cansend data messages over a data channel of a cellular telephone networkby altering the mobile identification number (MIN) or electronic serialnumber (ESN) of the cellular transmitter. By altering these cellulartransmitter identifiers, the messaging unit can send information overexisting cellular telecommunications equipment without opening a voicechannel or dedicated data channel.

Still another important advantage of the invention is that messagingunits can send data messages over a data channel of a cellular telephonenetwork by issuing a feature request with appended data digits. Thefeature request is then routed through a data channel of a cellulartelephone network to a remote data message gathering location.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the invention and the advantagesthereof, reference is now made to the following description taken inconjunction with the accompanying drawings, wherein:

FIG. 1 is a block diagram of a communications network for communicatinga variety of data messages in accordance with the teachings of theinvention;

FIG. 2 is a block diagram of a messaging unit operating within thecommunications network for sending and receiving a variety of datamessages in accordance with the teachings of the invention;

FIG. 3 is a flow diagram for sending a data message over a voice channelof the communications network using a modem handshake protocol inaccordance with the teachings of the invention;

FIG. 4 is a flow diagram for sending a data message over a data channelof the communications network in accordance with the teachings of theinvention;

FIG. 5 illustrates a block diagram of a nationwide cellular systemconstructed according to the teachings of the present invention;

FIG. 6 illustrates another embodiment of a nationwide cellular systemconstructed according to the teachings of the present invention;

FIG. 7 illustrates a mobile unit constructed according to the teachingsof the present invention;

FIG. 8 illustrates a telecommunications platform constructed accordingto the teachings of the present invention;

FIG. 9 is a flow diagram for transmission and reception of a presentmessage according to the teachings of the present invention;

FIG. 10 is a flow diagram of a call to a mobile unit according to theteachings of the present invention;

FIG. 11 is a flow diagram of a call from a mobile unit according to theteachings of the present invention; and

FIG. 12 is a block diagram of a central host constructed according tothe teachings of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a block diagram of a communications network 10. Located withincellular System 14 of network 10 is a truck trailer 12 carried by a cab,barge, train, or other suitable transportation system. It should beunderstood that the invention contemplates data messaging from any groupof cargo containers, vehicles, persons, and other items whose locationand status information are to be monitored.

Network 10 may be a cellular telephone network, but it may also beanother type of communications system, such as a specialized mobileradio (SMR) system, a personal communication services (PCS) system, orany other suitable communications system. Furthermore, network 10 may becomprised of land-based transmission towers, space-based satellitetransponders, or a combination of communications hardware in space or onland. Transmissions over network 10 may be analog or digital withoutdeparting from the scope of the invention.

Truck trailer 12 is equipped with a messaging unit 16, which contains acellular transceiver for sending and receiving data messages. The designof messaging unit 16 is discussed in detail with reference to FIG. 2.Cellular system 14 includes a transmission tower 18 and a mobiletelecommunications switching office (MTSO) 20 coupled to thetransmission tower 18. It should be understood that each cellular system14 may comprise a plurality of transmission towers and a plurality ofMTSOs.

MTSO 20 switches calls to and from the cellular system 14 and aland-based telecommunications system (not shown). MTSO 20 is alsocoupled to clearinghouse 22, which provides call information to MTSO 20through data link 23. For example, MTSO 20 can be configured to connectcalls only if clearinghouse 22 provides, for example, validationinformation indicating that the cellular phone involved has good creditor is authorized to make calls. Clearinghouse 22 may also maintain otherinformation, such as "roaming" phones' present locations and homesystems. In existing cellular systems, companies such as GTE/TSI, EDS,and McCaw provide the clearinghouse function.

MTSO 20 is coupled to a telecommunications platform ("platform") 24through a voice/data link 21. Clearinghouse 22 is also coupled toplatform 24 through data link 27 to provide platform 24 with informationgenerated by clearinghouse 22. In turn, platform 24 is coupled to host26 through voice/data link 29. Platform 24 may be coupled to any otherhost, such as host 28, through a similar voice/data link. Alternatively,hosts 26 and 28 may receive call information directly from clearinghouse22 over data link 31.

Hosts 26 and 28 are shown for clarity, but it should be understood thatmany other hosts may be similarly coupled to platform 24, otherplatforms, other hosts, or clearinghouse 22. Link 33 between host 26 andhost 28 allows hosts to exchange information. Host 35 may be connectedto host 28 via link 33, such that host 35 receives information solelyfrom host 28. In such a manner, designated hosts in network 10 act ascentral hosts to receive data messages and distribute these messages toother hosts.

FIG. 1 illustrates another cellular system 30, which includes a separatetransmission tower 18 and MTSO 20. Within the operating region ofcellular system 30 are truck trailers 12 equipped with messaging units16. A platform 25 may be associated with cellular system 30,illustrating that the platform functions can be performed at distributedlocations throughout network 10. However, platform 24 may perform allplatform functions for all cellular systems. Moreover, as shown in FIG.1, platform 24 may be coupled to one or more cellular systems. Forexample, platform 24 may be coupled to all of the east coast cellularsystems. Likewise, platform 25 is a distributed platform, and isassociated with and part of a particular cellular system. Platform 25,like platform 24, is coupled to a host, such as host 28.

Dashed line 32 indicates a link between MTSO 20 and platform 24. With aproposed standard (IS41, revision A), validation of a user can beperformed prior to the placing of cellular calls. For example, at powerup or upon first entry into a particular cellular system, a cellulartransceiver can issue identifiers to MTSO 20 for pre-validation.Alternatively, MTSO 20 can poll a cellular transceiver to provideidentifiers for validation and registration. The pre-validationinformation may be transmitted from MTSO 20 to clearinghouse 22 overdata link 23. Likewise, platform 24 may perform the pre-validationwithout resort to an outside clearinghouse, over link 32. With pre-callvalidation performed by clearinghouse 22, later data messages can besent directly to platform 24 over link 32. It should be understood thatlink 32 may be the same as voice/data link 21, a separate dedicated datalink, or another communications link.

Data link 34 between platform 24 to platform 25 allows distributedplatforms to exchange information regarding user validation, fraudmanagement, systems operation, and billing functions. The distributedplatform embodiment also provides fault tolerant and traffic managementfeatures in network 10, not unlike those features found in conventionallong-distance telephone systems. Thus, as is shown in FIG. 1,telecommunications platforms may be centrally located or arranged in adistributed manner and connected by data link 34.

Throughout this description of the invention, host 26, platform 24,clearinghouse 22, MTSO 20, and cellular system 14 have been discussed asseparate elements. It should be understood that each of these componentsare logical components, and they may be combined without physicalseparation. For example, the functions of platform 24 and host 26 may beaccomplished at a single site. Furthermore, the functions of platform 24and clearinghouse 22 may also be accomplished at a single site.References to cellular system 14, MTSO 20, clearinghouse 22, platform24, and host 26 are to be understood as also referring to any cellularsystem, switch, clearinghouse, platform, and host, respectively, ofnetwork 10.

Also illustrated in FIG. 1 is data link 36, which allows for datatransfer between MTSOs of the cellular systems in network 10. Such alink may be an SS7 backbone link for linking cellular systems. Link 36allows cellular systems to share information relating to validation,roaming, billing, call routing, and other functions performed by network10. For example, one cellular system that knows the location of aparticular cellular transceiver, such as the cellular transceiver inmessaging unit 16, may share that information with other cellularsystems. Platform 24 may tie into link 36 across link 21 or link 32 toaccess information exchanged among MTSOs of the cellular systems innetwork 10.

The description of FIG. 1 references both data links and voice/datalinks. Data links, such as links 23, 27, 31, 34, and 36, allowtransmission of data over a dedicated data channel. Voice/data links,such as links 21 and 29, support transmission of voice over a voicechannel and transmission of data over a data channel. For example, acellular telephone transmission over a voice/data link, such as a T1transmission link, may employ digital transmission techniques to carryvoice over a voice channel and data over a data channel, such as anoverhead message stream. It should be understood that the inventioncontemplates any transmission technique over a voice/data link, whetherdigital or analog, that provides a voice channel and a data channel.Current systems used in the industry include the DS-1 standard used inthe United States and the CCITT primary multiplex standard used inEuropean telecommunication systems.

Another communications protocol contemplated by the invention, termedcellular digital packet data (CDPD), sends data in packets interspersedbetween voice transmissions. The data messages in this protocol may becarried in a reserved section of the digital bit stream or selectivelyplaced to fill unoccupied sections of the digital bit stream. CDPDtechnology also supports delivery of data messages that is notreal-time. This is accomplished by establishing delivery addresses, so auser may receive and store data messages at a designated address andretrieve the data messages at a later time for processing.

Voice/data links also support transmission of data over a voice channelusing a modem, dual-tone multifrequency ("DTMF") tones, or othersuitable data encoder. The invention contemplates two ways to send adata message in network 10, data transmission over a data channel anddata transmission over a voice channel using a data encoder. It shouldbe understood that a dedicated data channel, such as link 34, could bereplaced with a link that also allows voice transmission, withoutdeparting from the intended scope of the present invention.

In operation, network 10 allows data messages to be sent across cellularsystems, such as cellular systems 14 and 30, in a variety of ways. Datamessages sent to or received from messaging units 16 over a voicechannel in network 10 must pass through platform 24 or 25, where theyare subject to a handshake protocol to minimize cellular telephone fraudand maintain secured communications.

Data messages may also be sent to or received from messaging unit 16over a data channel in network 10. As described below, these messagesare packaged and sent over a data channel as part of the call dataprocessing procedures. Like data messages sent over a voice channel ofnetwork 10, data messages sent over a data channel may also be subjectto a security protocol. Each type of data messaging supported by network10 will be discussed in detail with reference to FIGS. 3 and 4.

FIG. 2 is a block diagram of a messaging unit 16 operating withinnetwork 10 of FIG. 1. In one embodiment of the invention, messaging unit16 may be attached to truck trailer 12. However, it should be understoodthat data messaging in network 10 is not limited to truck trailermonitoring systems. Messaging unit 16 may be attached to any mobileitems to be monitored, such as people, vehicles, or cargo containers.

As shown in FIG. 2, cellular transceiver 38 is coupled to cellulartransceiver bus 40. Cellular transceiver 38 receives and transmitssignals across cellular antenna 42, including cellular transmission andreception of voice and data over the voice and data channels in network10. Cellular transceiver 38 may be just a cellular transmitter equippedto transmit data messages or just a receiver equipped to receive datamessages. It should be understood that further references to cellulartransceiver 38 contemplate a transmitter, a receiver, or both.

Cellular transceiver bus 40 is coupled to one or more processors 44through cellular interface drivers 46. Cellular interface drivers 46provide the necessary protocol for communications between processor 44and cellular transceiver 38.

A modem 48 allows processor 44 to receive and transmit digitalcommunication over a voice channel in network 10, as received from andtransmitted through cellular antenna 42 and cellular transceiver 38.Modem 48, or any suitable device, distinguishes between voice and dataencoded on the voice channel, and handles the information accordingly.

Processor 44 is also coupled to a DTMF recognizer 50. DTMF recognizer 50allows reception and transmission of DTMF data over a voice channel ofnetwork 10, as received from and transmitted through cellular antenna 42and cellular transceiver 38. All data transmissions to or from messagingunit 16 can be made using DTMF data.

Processor 44 is also coupled to a read-only memory ("ROM") 52 and arandom access memory ("RAM") 54. These memories are for storage ofinstructions and data for operation of processor 44. It should beunderstood that the invention contemplates use of any other suitablestorage devices (not shown) including, but not limited to, hard disk andfloppy disk drives, optical disk drives, CD-ROM storage devices, tapebackups, and plug-in memory modules. A real-time clock 56 providesprocessor 44 with time-of-day, day-of-week, month, or year information.

Messaging unit 16 allows for input of location information from aLORAN-C system, global positioning satellite (GPS) system, deadreckoning system, inertial navigation system, or any suitable systemproviding location information. A positioning system interface 58provides location information to processor 44, as received frompositioning system transceiver 60 through positioning system antenna 62.The location information sent to processor 44 from the positioningsystem can be either raw location data (for example, data directlyreceived from a LORAN-C system) or processed location data. Therefore,the processing of raw location data can occur within the positioningsystem itself, within the positioning system interface 58, withinprocessor 44, or transmitted through cellular transceiver 38 andcellular antenna 42 for later processing at platform 24 or host 26 ofFIG. 1.

Messaging unit 16 also allows for input of status information throughsensor system 64. In one embodiment, sensor system 64 comprises sensors,controllers, and processors used to monitor various parameters of trucktrailer 12, and operates to pass status information to processor 44.Sensor system 64 may monitor performance parameters of truck trailer 12,such as the temperature of a refrigerated compartment, battery voltagelevels, or diagnostics of other truck trailer subsystems. Sensor system64 may also monitor the status of truck trailer 12 and its contents,such as whether truck trailer 12 is connected to a cab and whether thecontents have been tampered with. For purposes of this description,"sensor" refers to any device that furnishes processor 44 with locationand status information, including a positioning system.

A power supply 66 powers the various components of messaging unit 16.For clarity, the power connections to the different components ofmessaging unit 16 are not shown. Power supply 66 is a power managementsystem which may include a battery and charging circuitry. In addition,power supply 66 may include optional sources of power, such as anexternal power connection 68 from, for example, a truck electricalsystem interconnection cable or a solar cell 70 mounted on the roof oftruck trailer 12.

As shown in the particular embodiment of FIG. 2, solar cell 70, cellularantenna 42, and positioning system antenna 62 may be mounted directly onthe truck trailer roof, while the other components of messaging unit 16reside inside the cargo compartment. However, it should be understoodthat the invention contemplates any arrangement and placement of thecomponents of messaging unit 16 in one or more separate housingsattached to the mobile item to be monitored.

In operation, messaging unit 16 generates a data message to be sent overvoice or data channels of network 10 upon the occurrence of a reportingevent. The occurrence of a reporting event is determined by processor 44executing a reporting event determination module 72, shown as a part ofprocessor 44 in FIG. 2. Upon the occurrence of a reporting event,processor 44 may immediately generate and transmit a data message orgenerate and store the data message for later transmission. By storingdata messages, messaging unit 16 may then send a batch of data messageschronicling the status of truck trailer 12 over a period of time.

One reporting event that may trigger generation of a data message is atime-out signal received by processor 44 from real-time clock 56.Therefore, messaging unit 16 may generate data messages and reportlocation and status information for truck trailer 12 at a particulartime interval, such as twice a day, every day, or every week. Inaddition, a reporting event may be an external request from a variety ofsources, such as MTSO 20, clearinghouse 22, platform 24 and host 26,among others.

A reporting event may also be initiated by the truck trailertransportation equipment or its operator. For example, messaging unit 16may generate and transmit a data message upon a signal, received byprocessor 44 from sensor system 64, indicating connection ordisconnection from the cab. An operator of the transportation equipmentmay also manually request messaging unit 16 to send a data message.

A reporting event may occur in response to a performance or alarm signalreceived by sensor system 64 that is beyond predetermined limits. Forexample, a reporting event may be when the cargo temperature in arefrigerated truck trailer exceeds a certain minimum or maximum level.The predetermined limits that trigger a reporting event may be remotelyconfigured from the clearinghouse 22, platform 24, or host 26. Processor44 may also determine a reporting event upon improper access to thecargo hold, malfunctioning of truck trailer subsystems, ormalfunctioning of messaging unit 16 itself.

Furthermore, a reporting event may be based on geographical information.For example, messaging unit 16 may generate a data message when thetruck trailer location determined by the positioning system deviatesfrom an expected truck trailer location. The expected location may bestored in memory such as ROM 52, RAM 54, or other storage device,computed by processor 44, or received from host 26 or platform 24.

In a similar manner, a reporting event may occur when truck trailer 12approaches or crosses a city, state, or national border, or enters theservice area of a cellular system. Therefore, processor 44 executingreporting event determination module 72 causes messaging unit 16 togenerate a data message upon the occurrence of a reporting event. Thereporting event may be based on time, external requests, sensor inputs,manual requests by the driver, geographical information, or any otherevent or condition that warrants reporting of a data message to host 26.

Upon determination of a reporting event, messaging unit 16 operates totransmit and receive a variety of data messages over network 10. Thedata messages may contain information that initiated the reportingevent, such as a signal indicating connection of the truck trailer to acab, and also other monitored information, such as the location of thetruck trailer at the time of the reporting event. Ultimately datamessages transmitted from messaging unit 16 are routed through platform24, clearinghouse 22, or both and accessed by host 26, as shown inFIG. 1. A data message may be communicated over network 10 using eithera voice channel or a data channel.

Messaging unit 16, through control of processor 44 may transmit andreceive data messages over a voice channel through platform 24. Forclarity, the transmission or reception of data messages over a voicechannel, including handshaking, will be discussed in connection withmodem transfers, it being understood that such transmissions can be madeusing DTMF tones or other data encoded on the voice channel.

The ability to require that all data messages communicated over a voicechannel pass through platform 24 is an important advantage of theinvention, and allows for modem handshaking between platform 24 andmessaging unit 16. As shown in FIG. 2, processor 44 runs instructionsthat execute a handshake protocol module 74 which establishes securedata modem communication with platform 24. The method to transmit datamessages over a voice channel is described in more detail with referenceto FIG. 3.

Processor 44 also executes a MIN statusing module 76 and a featurerequest generation module 78, which allow messaging unit 16 to generateand transmit data messages over a data channel of network 10. Asdescribed below with reference to FIG. 4, MIN statusing module 76 allowsmessaging unit 16 to encode status and location information by alteringidentifiers of cellular transceiver 38, such as the mobileidentification number (MIN) or electronic serial number (ESN),transmitted over a data channel of network 10. Feature requestgeneration module 78, also discussed with reference to FIG. 4, isanother method to send data messages over a data channel by appending toa feature request data digits representing status and locationinformation.

Link 80 between processor 44 and the transportation system allowsmessaging unit 16 to send and receive communications to and from, forexample, a truck cab. The link may allow two-way communications using ashort range radio system, an infra-red (IR) coupling, a directconnection through signal wires, or other appropriate technology.Alternatively, the link may be a one-way communications link that allowsmessaging unit 16 to send data messages for transmission by thetransportation system. In one embodiment, a one-way link may allow ascanner attached to the transportation system to identify the attachedtruck trailer 12.

Functionally, link 80 allows components of messaging unit 16 to bedivided between the mobile item and its transportation system. In oneembodiment, processor 44 residing on the mobile item generates a datamessage and then sends this data message over link 80 for transmissionby cellular transceiver 38 located on the transportation system. In sucha manner, the cost of outfitting mobile items with data messagingcapabilities may be reduced by placing components of messaging unit 16on the transportation system. It should be understood that the inventioncontemplates any arrangement of components of messaging unit 16 on themobile item and the transportation system.

FIG. 3 is a flow diagram for sending a data message generated bymessaging unit 16 over a voice channel of network 10 using a modemhandshake protocol. The method begins at block 100 which determineswhether one of a variety of reporting events has occurred, as determinedby processor 44 running reporting event determination module 72. If noreporting event has occurred, the method loops back in a continuousfashion to monitor the existence of a reporting event. When a reportingevent occurs, block 102 generates a data message. The data message maycontain location and status information of truck trailer 12 in astandard data package for transmission by modem 48. It should beunderstood that the invention contemplates any suitable modem transferprotocol and compression technique to prepare the data for transmissionby modem 48.

The method of FIG. 3 then proceeds to block 104 where messaging unit 16establishes a data modem connection with platform 24 over a voicechannel of voice/data link 21 or 32. Data modem connection establishesthe parameters for communication, such as baud rate, parity, and numberof stop bits. After the connection is established, block 106 initiates amodem handshake between messaging unit 16 and platform 24. If messagingunit 16 does not pass the modem handshake and establish securecommunications with platform 24, the method proceeds to block 108, wherethe communication is disconnected. At block 110, messaging unit 16 maytry to reestablish a data modem connection and retry modem handshaking.Alternatively, the process may be reset for detection of anotherreporting event at block 100.

Upon successful modem handshake, the method proceeds to block 112 wheremodem 48 downloads the contents of the data message into a storagedevice in platform 24. The data may be time-stamped and stored as anentry in a log of data messages from messaging unit 16. Platform 24 canalso index received data messages by an identification number ofmessaging unit 16 or cellular transceiver 38 received during modemhandshaking at block 106. At block 114, an external device, such as adispatcher's computer at host 26, can access the stored data messagesand update a record of the location and status of mobile items equippedwith messaging unit 16.

FIG. 4 is a flow diagram for sending a data message over a data channelof network 10 using either the MIN statusing 76 or feature requestgeneration 78 modules of processor 44. Unlike data messaging using modemdata or DTMF tones, the following discussion describes transmission ofdata messages through network 10 without opening a voice channel.Furthermore, the data messaging techniques described below can be routedthrough clearinghouse 22, platform 24, or both clearinghouse 22 andplatform 24.

The method of FIG. 4 begins at block 116 which determines whether areporting event has occurred by executing reporting event determinationmodule 72 in processor 44. If no reporting event has occurred, themethod continues to monitor sensor system 64, real-time clock 56,location data received from positioning system interface 58, and otherinputs to determine if a reporting event has occurred.

Upon the occurrence of a reporting event, block 118 generates a datamessage. As described above, data messages may be created and sentimmediately or created and stored for later transmission by messagingunit 16. A data message for transmission over a data channel of network10 may be generated in two ways. First, location and status informationcan be encoded by altering identifiers of cellular transceiver 38, suchas the mobile identification number (MIN) or electronic serial number(ESN). A second way to generate a data message is by dialing a featurerequest and appending location and status information in digits of datawithin the feature request. These two different ways of generating adata message are described in detail below.

The process to alter identifiers of a cellular transceiver 38 totransmit a data message, termed MIN statusing, begins withidentification of the event to be reported and a translation of thisevent into a coded number. For example, assume processor 44 of messagingunit 16 receives a reporting event signal from sensor system 64indicating that the temperature in the refrigerator compartment of trucktrailer 12 is too high. Processor 44 translates the reporting eventinto, for example, a two-digit status code "39". The MIN of cellulartransceiver 38 may be altered to include status code "39" in adesignated data field. For example, if the current MIN is "099 8811234", then the new altered MIN with the embedded status code may be"099 880 0039". The prefix "880" indicates that the MIN has been alteredto convey status or location information, and the last four digitscontain the encoded location or status information in the form of atwo-digit status code "39".

The MIN of cellular transceiver 38 is altered to include a data message,but the ESN remains fixed to be used as an identifier of the messagingunit 16 that sends the data message. Therefore, upon receipt of theMIN/ESN, clearinghouse 22 or platform 24 can identify the messaging unit16 by the ESN and can also receive status and location informationencoded in the MIN. Alternatively, processor 44 can alter the ESN ofcellular transceiver 38 and keep the MIN constant. It should beunderstood that the invention contemplates modification of the MIN, ESN,both the MIN and ESN, or other identifiers of cellular transceiver 38 toaccomplish the dual task of encoding location or status information andidentifying messaging unit 16.

Cellular transceiver 38 may transmit identifiers to MTSO 20 upon a call,feature request, pre-call validation, or other communication betweencellular transceiver 38 and MTSO 20. Therefore, the MIN statusingtechniques of the invention can be used alone or in connection withfeature request data messaging, data messaging over a voice channel ofnetwork 10, or any other data messaging technique that also transmitsidentifiers of cellular transceiver 38.

A second way to generate a data message at block 118 is to use a featurerequest and append location and status information in designated datadigits of the feature request. Feature requests come in severalvarieties. For example, some feature requests are intercepted and actedupon by MTSO 20, such as "*18" and "*19" used to establish anddisconnect roaming services. Other feature requests, such as programmedspeed dial numbers, are equivalent to dialing a telephone number.

A dedicated feature request intercepted by MTSO 20 may be specificallyimplemented to transmit data messages. Such dedicated feature requestsallow messaging unit 16 to send detailed data messages containing, forexample, accurate location information generated by the positioningsystem. As an example, a data messaging feature request termed "*71" isgenerated by automatically or manually dialing the star key "*", atwo-digit feature request identification code "71", and 29 digits ofdata. Furthermore, cellular transceiver 38 automatically appends theMIN/ESN to a feature request transmission. Such a feature requestgenerated by messaging unit 16 and sent over a data channel of thecellular system would allow appended data messages of up to 29 digits.

Upon generating a data message using either MIN statusing 76 or featurerequest generation 78, the method of FIG. 4 proceeds to block 120 whereMTSO 20 receives the data message. MTSO 20 may directly recognize theMIN/ESN or feature request identification code as identifying a datamessage from messaging unit 16. For example, MTSO 20 may be directed torecognize and process in a special manner all communications from aparticular predetermined MIN/ESN, such as all MINs beginning with "099880". Alternatively, MTSO 20 may be directed to recognize and process ina special manner all feature request transmissions with a particularfeature request identification code, such as "71".

In another embodiment, MTSO 20 may contain a separate processor thatindirectly monitors the call transactions through MTSO 20. The separateprocessor may also recognize and process data messages from messagingunit 16 in the same manner described above. In either situation, MTSO 20appends a mobile serving carrier I.D. ("MSCID") to the MIN/ESN at block122 and routes the data message to clearinghouse 22 over data link 23 orplatform 24 over voice/data link 21 or 32.

In one embodiment, the data message is received directly atclearinghouse 22, as shown in block 124. In another embodiment shown inblock 126, the data message is received at platform 24 directly throughvoice/data links 21 or 32, or indirectly through data link 27 fromclearinghouse 22. An optional security protocol is performed at block127 to ensure the authenticity of the data message. At block 128, themethod identifies the particular messaging unit 16 that is reporting thedata message using the MIN/ESN or other identifiers of cellulartransceiver 38 or messaging unit 16. The data message is then translatedor decoded to determine the status or location information reported bymessaging unit 16.

The method of FIG. 4 continues at block 130 where each data message maybe time-stamped, indexed by identification number, and stored for laterretrieval. The method of FIG. 4 concludes at block 132, where anexternal device, such as a dispatcher's computer at host 26, can accessthe stored data messages and update a record of the location and statusof items equipped with messaging unit 16, and thus allow appropriateresponses to the data messages.

Throughout the discussion of FIGS. 3 and 4, the data messages aretransmitted by messaging unit 16 to be collected at a central location,such as clearinghouse 22, platform 24, or host 26. It should beunderstood that messaging unit 16 equipped with cellular transceiver 38may also receive data messages from a central location. The datamessages may be sent from a central location to messaging unit 16 over avoice or data channel of network 10 and in a similar manner as describedabove with reference to FIGS. 3 and 4. For example, data messagesreceived by messaging unit 16 may be sent over a data channel using MINstatusing or feature request generation, or over a voice channel using adata encoder, such as a modem or DTMF recognizer. Received data messagesat messaging unit 16 may serve a variety of functions, such as remotelyprogramming predetermined sensor reporting limits, updating messagingunit 16 software, requesting information, or alerting the operator ofthe transportation system, among others.

FIG. 5 is a block diagram of a nation-wide cellular network 210constructed according to the teachings of the present invention. Asshown in FIG. 5, a vehicle 212 is within cellular system 214. Vehicle212 includes a mobile unit 216, which will be discussed in detail below.Cellular system 214 includes transmission towers 218 (only one tower isshown for clarity, it being understood that each cellular systemincludes a plurality of transmission towers). Cellular system 214 alsoincludes a central mobile telecommunications switching office (MTSO) 220coupled to the transmission tower 218.

MTSO 220 switches calls to and from the cellular system 214 and the landbased telecommunications system. MTSO 220 is also coupled toclearinghouse 222. The link between MTSO 220 and clearinghouse 222 is adata link, and clearinghouse 222 provides call validation information toMTSO 220. For example, MTSO 220 can be configured to connect calls onlyif clearinghouse 222 provides validation information on the call, suchas that the cellular phone involved has good credit, or is authorized tomake calls. Clearinghouse 222 may also maintain other information, suchas information on "roaming" phones' present locations, and home systems.In existing cellular systems, companies such as GTE/TSI, EDS, and McCawprovide the clearinghouse function.

MTSO 220 is also coupled to telecommunications platform ("platform") 224through a telecommunications link 221 allowing both voice and datatransmissions. Clearinghouse 222 is also coupled to platform 224. Inturn, platform 224 is coupled to central hosts 226 and 228. Centralhosts 226 and 228 are shown for clarity. It should be understood thatmany other central hosts may be similarly coupled to platform 224.Furthermore, other cellular systems will also be coupled totelecommunications platform 224. For clarity, FIG. 5 illustrates oneother such cellular system, cellular system 230. As shown, cellularsystem 230 also includes transmission towers and an MTSO.

Dashed line 232 indicates a link between MTSO 220 and platform 224. Witha proposed standard (IS41, revision A), validation of calls can beperformed prior to the placing of cellular calls. For example, at powerup, or upon first entry into a particular cellular system, a cellularphone can issue its identification numbers, and pre-validation can beperformed. Alternatively, the MTSO 220 can poll mobile unit 216 torequest identification for validation and registration. Thepre-validation may be between MTSO 220 and a clearinghouse, such asclearinghouse 222. Likewise, platform 224 may perform the pre-validationwithout resort to an outside clearinghouse, over link 232. With pre-callvalidation performed by clearinghouse 222, later data transmissions,such as feature requests, can be sent directly to platform 224 over link232. It should be understood that link 232 may be the same as link 221.

In operation, nation-wide cellular network 210 operates to controlaccess to and information sent across cellular systems such as cellularsystems 214 and 230. In particular, all calls to or from mobile unit 216must pass through telecommunications platform 224. Therefore, calls toand from mobile unit 216 are controlled to limit access to and time oncellular system 214. The details of this control will be discussedbelow.

FIG. 6 illustrates an alternate embodiment of the present inventionwhich includes distributed telecommunications platforms. FIG. 6 includesthe elements described above in connection with FIG. 5, with theexception that the telecommunications platform is distributed.Illustrated in FIG. 6 are platforms 234 and 236. In contrast to platform224 of FIG. 5, which is centrally located and to which all cellularsystems are connected, platforms 234 and 236 may be distributedthroughout the nation-wide cellular network. As shown in FIG. 6,platform 234 may be coupled to one or more cellular systems. Forexample, platform 234 may be coupled to all of the east coast cellularsystems. Likewise, platform 236 is a distributed platform, and isassociated with and part of a particular cellular system.

Also shown in FIG. 6 is a communications link 237 from platform 234 toplatform 236 that allows the distributed platforms to exchange voice anddata, which may include user activity, systems operation, and billingfunctions. In particular, the distributed platforms 234 and 236 canexchange information regarding user validation and fraud management. Thedistributed platform embodiment also provides fault tolerant and trafficmanagement features to the nation-wide cellular telephone system, notunlike those features found in conventional long-distance telephonesystems. Thus, as is shown in FIGS. 5 and 6, telecommunicationsplatforms may be centrally located or distributed, as required by theneeds of the particular system implementing the present invention.

Also illustrated in FIG. 6 is link 239. Link 239 allows for datatransfer between MTSOs of various cellular systems. Such a link may bean SS7 backbone link for linking cellular systems. Link 239 allowscellular systems to share information such as validation, roaminginformation, billing, and call routing, among other types ofinformation. For example, one cellular system that knows the location ofa particular cellular phone, such as mobile unit 216, may share thatinformation with other cellular systems. Platform 224, across link 232,may tie into link 239. This allows platform 224 to have access to allMTSO 220s of different cellular systems.

FIG. 7 illustrates a mobile unit 216 constructed according to theteachings of the present invention. As shown in FIG. 7, phonetransceiver 238 and hand set 240 are coupled to cellular phone bus 242.Phone transceiver 238 receives and transmits signals across antenna 244,including cellular transmission and reception of voice, data, and DTMFdata, among other signals. The cellular phone bus 242 is coupled toprocessor 246 through phone interface drivers 248. Phone interfacedrivers 248 provide the necessary protocol for communications betweenthe processor 246 and the phone transceiver 238 and hand set 240.

A hands-free microphone 250 and speaker 252 are provided for hands-freecommunications by the operator of the mobile unit. The hands-freemicrophone 250 and speaker 252 are coupled to audio multiplexer 254.Audio multiplexer 254 is also coupled to the hand set 240, the cellularphone bus 242, and the processor 246. The audio multiplexer 254 is alsocoupled to a modem 256 and a voice recognition and synthesis system 258.The modem 256 allows for digital communication between the processor 246and the cellular system, as received from and transmitted throughantenna 244 and phone transceiver 238. Modem 256, or any suitabledevice, is used to distinguish between voice and data and handle theinformation accordingly. Voice recognition and synthesis system 258allows for voice activation of various functions of the mobile unit.Voice recognition and synthesis system 258 is coupled to processor 246.

Processor 246 and audio multiplexer 254 are also coupled to a dual-tonemulti-frequency ("DTMF") recognizer 259, which allows for recognition ofDTMF data. All data transmissions to or from mobile unit 216 can be madeusing DTMF.

Mobile unit 216 also allows for reception and storing of telephonenumbers. These numbers may be received as modem or DTMF data, and may berecalled and automatically dialed. Furthermore, processor 246 of mobileunit 216 can execute software allowing for voice mail functions forcalls to mobile unit 216.

Processor 246 is also coupled to a read-only memory 260 and a randomaccess memory 262. These memories are for storage of instructions anddata for operation of processor 246. Furthermore, a plug-in ROM module264 may also be coupled to processor 246 for optional information, suchas map and emergency assistance information for a particular locality.

A key pad 266 is provided for user input of various information into themobile unit 216 through processor 246. It should be understood that keypad 266 could comprise many other input devices, such as a touch screen.Information is displayed at mobile unit 216 through graphic display 268,which is driven by processor 246 through display drive 270.

Mobile unit 216 allows for input of location information from a LORAN-Csystem, a global positioning satellite (GPS) system or any suitablesystem providing location information of the mobile unit. This input isshown by positioning system 272 in FIG. 7. The positioning system 272may be located within the housing of the mobile unit 216, or part or allof positioning system 272 may be located outside the mobile unit 216.The data sent to the mobile unit 216 from positioning system 272 can beeither raw location data (for example, data directly received fromLORAN-C system) or processed location data. Therefore, the processing ofraw location data can occur within the positioning system 272 itself,within processor 246, or transmitted through phone transceiver 238 andantenna 244 for later processing at the platform 224 or central host 226of FIG. 5.

Mobile unit 216 also allows for input of status information throughautomatic status generator 274. The automatic status generator 274comprises any sensors, controllers, and processors used to monitorperformance parameters of the vehicle 212, and operates to passinformation from such monitors to the mobile unit 216. As will bediscussed, status information may be received by the mobile unit 216from either the automatic status generator 274 or the key pad 266. Block276 allows for the input or output of various other options, such as analarm input which, for example, could indicate that a vehicle on whichthe mobile unit is located has been broken into. As other examples,block 276 allows for the input or output of fax data or digital data toor from a modem. Such inputs and outputs may be from personal computers,for example, from users of recreational vehicles or traveling salesmen.Throughout this discussion, data communications, including handshaking,will be discussed in connection with modem transfers for clarity, itbeing understood that such transmissions can be made as DTMF data. Apower supply 278 powers the mobile unit 216.

In operation, mobile unit 216 operates to transmit and receiveinformation, including voice and data, across a cellular system andthrough telecommunications platform 224 of FIG. 5. Ultimately, datatransmitted from mobile unit 216 is sent through platform 224 to one ofthe central hosts, for example central hosts 226 or 228 shown in FIG. 5.

Mobile unit 216, through control of processor 246, receives all callsthrough telecommunications platform 224, and makes all outgoing callsthrough telecommunications platform 224. This restriction isaccomplished through use of a handshake protocol. The details of thisprotocol will be discussed below in connection with calls to or from themobile unit. The ability to require that all calls to and from themobile unit pass through platform 224 is an important advantage of thepresent invention, and allows for control of the character and length ofcalls made to and from the mobile unit. This is important in reducingcellular telephone usage costs, for example for a nation-wide truckingcompany, in which the trucking company provides mobile units in each ofthe trucks of the fleet, and wishes to restrict the character and lengthof calls from and to the mobile units.

The mobile unit 216 allows for transmission and reception of both voiceand data. The voice transmissions, once a call is connected, areperformed conventionally. Hands-free microphone 250 and speaker 252allow for hands-free voice communications.

Data received by remote unit 216 is input to the processor 246 throughmodem 256. Data transmitted from mobile unit 216 is transmitted undercontrol of the processor 246 through modem 256. Data to be transmittedfrom mobile unit 216 may be input in several ways. Key pad 266 may beused by a user of the mobile unit 216 to input various data, such aslocation data or status data (for example, whether a vehicle is brokendown, whether it is loading, unloaded, waiting to load, waiting tounload, etc.). Such data may also be input by voice command throughvoice recognition and synthesis system 258. Data may also beautomatically generated for output by mobile unit 216. For example,positioning system 272, which may comprise a LORAN-C positioning system,a GPS system, or any other positioning system, may generate positionlocation information for transmission by mobile unit 216.

As discussed above, positioning system 272 may generate longitude andlatitude information, or simply raw data, for example from a GPS system,to be transmitted from mobile unit 216. If only raw data is generated bya positioning system 272, then processor 246, the platform 224, or thecentral host 226 can generate the longitude and latitude information forpositioning information. Likewise, automatic status generator 274 may beused to automatically generate status information, such as engineperformance, trailer temperature (for example, if a refrigerated trailertractor is associated with the remote unit), or other statusinformation.

Processor 246 drives graphic display 268 through display driver 270 todisplay data received by mobile unit 216 for viewing by a user of mobileunit 216. Such data, for example, may be messages from a central host onweather conditions, delivery or destination instructions, among othermessages. Furthermore, plug-in ROM 264 provides various information,such as map information or emergency assistance information for use by auser of the remote unit 216. This information can be displayed ongraphic display 268.

FIG. 8 illustrates a block diagram of telecommunications platform 224constructed according to the teachings of the present invention. Aprocessor 280 is coupled to memory 282, look-up tables 284, and switch286. Processor 280 is also coupled to fraud management system 287, usagetracking system 288 and billing system 290. In the distributed platformembodiment of FIG. 6, processor 280 may also communicate with anotherplatform through communications link 291. Switch 286 is coupled totelecommunications trunks 292 and 294. Trunk 292 allows fortelecommunications connections to central hosts, such as central hosts226 and 228 of FIG. 5, as well as other outside land based systems. Asshown in FIG. 8, some of the individual telecommunications lines oftrunk 292 are coupled to modems, such as modems 296 and 298, thusallowing for data communications. Likewise, trunk 294 allows fortelecommunications connections with various cellular systems, such ascellular systems 214 and 230 of FIG. 5. Some of the individualtelecommunications lines are coupled through modems, such as modems 300and 302, so as to allow for data communications with the cellularsystems. Modems 296 and 300 are illustrated as MODEM/DTMF, to indicatethat DTMF data can be transmitted and received as well. Modems 296, 298,300 and 302 are coupled to processor 280 and can also operate to allowboth voice and data communications. Trunks 292 and 294 are separated forclarity to show one bank of telecommunications lines serving dispatchersand other outside systems while another bank serves cellular systems.However, switch 286 can contain a single trunk or several trunks toaccomplish the operations of the platform.

Telecommunications platform 224 operates as a smart telecommunicationsswitch. Calls to and from remote unit 216 are passed through switch 286.Processor 280 monitors switch 286 and records information on each callthrough switch 286. This information, such as the number and length ofcalls to each remote unit 216, is recorded in usage tracking system 288.In this manner, bills can be generated for usage of telecommunicationsplatform 224. Typically there will be several remote units associatedwith a particular nation-wide system, such as a trucking system. Thus,all calls to and from remote units owned by that trucking system will belogged for billing to that particular trucking system.

As discussed previously, a fraud management system 287 performs ahandshake protocol between the telecommunications platform 224 and theremote unit 216. This protocol ensures than only authorized calls aremade to and from mobile unit 216. If the handshake protocol is notperformed correctly, then processor 280 will disconnect the call throughswitch 286, thereby greatly reducing costs resulting from unauthorizedusage of cellular networks. Processor 280 also links to credit cardvalidation system 303, to validate credit cards for allowing forpersonal calls, as will be discussed.

FIG. 9 is a flow diagram for transmission and reception of a "present"message according to the teachings of the present invention. Mobile unit216 of the present invention, upon entry into a new cellular system,issues a present message which will eventually be sent to its centralhost. The "present" message can also be generated in response to a pollfrom platform 224 or MTSO 220, periodically, upon power up of mobileunit 216 upon re-establishment of communication, through use of afeature request reserved for the "present" message, or during pre-callor post-call validation, among other events. This "present" message canalso be sent automatically or manually, and provides information to thecentral host on the current cellular system in which the mobile unit islocated. Furthermore, other information, such as status information, canbe sent with this "present" message. An important technical advantage ofthe present invention is the fact that this "present" message may besent automatically, and with a minimum of cellular air time, thusproviding significant cost savings. The "present" message may be sent toplatform 224 through clearinghouse 222, through link 221 (for example,as part of a call), or through link 232 of FIG. 5.

Turning to the flow diagram of FIG. 9, at decision block 304, mobileunit 216 monitors the system identification number of the particularcellular system in which it is located. This system identificationnumber, as is generally known in the art, is periodically issued by thecellular system in the overhead message stream. Once the remote unit 216identifies a new system identification number, indicating that themobile unit has entered a new system, it issues a "present" message atblock 306. For example, the "present" message can be initiated bytransmitting a "*19" feature request. Presently, "*19" is used in mobilesystems to clear the roaming status of a cellular phone. As discussedabove, the "present" message can also be generated upon other events,such as power up of the mobile unit 216.

Every cellular phone has associated with it a mobile identificationnumber ("MIN") and an electronic serial number ("ESN"). These numbersare transmitted by the cellular phone whenever it makes a call or issuesa feature request, such as "*19." Certain digits of the ESN are used bylocal cellular carriers. The unused digits may be used by mobile unit216 to send information, such as location or status data. For example,longitude and latitude data can be embedded in the unused portion of theESN. Likewise, certain digits of the MIN may not be necessary toidentify calls to be directed to platform 224, and thus data may beembedded in these unused digits. Thus, the "present" message may containimportant data as well. At block 308, the "present" message is receivedat MTSO 220 of FIG. 5. The MTSO 220 typically appends the cellularsystem identification number plus a switch identification number to theMIN and ESN numbers. As discussed, the "present" message may also besent as part of a call from the mobile unit 216, and thus is sent toplatform 224 across link 221.

When the "*19" is received at the clearing house 222 at block 310, itwill determine whether the "present" message is to be sent to thetelecommunications platform 224 at block 312. If the "present" messageis not to be sent to the platform, then no data is sent. Theclearinghouse 222 determines whether the "present" message is to be sentto the platform 224 by matching the MIN/ESN of the mobile unit tonumbers stored in a pre-established user data base. This data base isestablished by making arrangements with the clearinghouse 222 that allcommunications from particular cellular phones, i.e., the mobile units216, will be recognized by their MIN/ESN and directed to the platform224. This data base can also be established such that even with a mobileunit registered at some home cellular system, the "present" message willbe directed to the platform 24.

As discussed above, a direct link 232 may exist between MTSO 220 andplatform 224. This link 232 allows for direct transmission of data andfeature requests, such as the "*19" feature request and "present" datamessage, to the platform 224. MTSO 220 can be configured to directlysend such transmissions by pre-arranging with MTSO 220 to recognizeparticular mobile units 216, or by forwarding such instructions fromclearinghouse 222 as part of a pre-call validation scheme.

One embodiment allows the clearinghouse 222 to identify the mobile units216 by a specified area code and prefix of the MIN. Upon matching theregistered mobile units 216 with the user data base in the clearinghouse222, the "present" message is sent to the platform 224 at block 314. Theplatform then timestamps and stores all "present" messages received frommobile unit 216 through the local carrier. The platform stores the dataunder each MIN/ESN for later transmittal to the central host. Forexample, a single mobile unit 216 on a truck travelling across thecountry may send numerous "present" messages to the platform as thetruck passes through different cellular systems. The platform 224maintains a timstamped chronological list of the "present" messages, sothe truck company dispatch can access the list and determine thelocation and status of the truck.

The platform 224 of FIG. 8 eventually sends this information to theparticular central host associated with the mobile unit 216 as shown atblock 316. This transfer of data can occur periodically, such as at aparticular time interval, upon request by a central host, or whenever acall connection is made between a central host and the mobile unit 216.It should be understood that there will typically be a plurality ofmobile units associated with a particular central host. For example, thecentral host may be a truck company dispatch that locates andcoordinates the activities of a fleet of trucks equipped with mobileunits 216. Thus, data can be down loaded from the platform 224 to thetruck company dispatch anytime a call is made between the dispatch andany of the trucks. Alternatively, the truck company can periodicallycall the platform, preferably when call rates are low or on a dedicatedor "800" number, and download a data package containing status andlocation information on the truck fleet. From the "present" message, thecentral host can determine at least which cellular system a particularmobile unit has entered. This information is available since the MTSO220 appends information the MIN/ESN. Such information may be, forexample, a mobile serving carrier I.D. ("MSCID"). Furthermore, any data,including specific location data generated by positioning system 272,embedded in the ESN/MIN can be extracted by the central host.

The ability to generate "present" messages provides a significantadvantage of the present invention. In particular, one centrallocation--the platform 224--maintains these "present" messages and thushas knowledge of the location (at least the cellular system location) ofvarious mobile units. This information allows for efficient andinexpensive call delivery. By directing calls to the mobile unitsthrough the platform 224, roaming difficulties are eliminated, since theplatform 224 maintains a record of the locations of the mobile units216. This call delivery advantage is useful in a wide range ofapplications, such as the broadcasting of messages to distributed mobileunits, like those used in trucking companies, barges, travelling salesforces, rail systems, commercial and private bus lines, airplanes, andrental vehicles, among others. The architecture of the present inventionalso allows for efficient broadcasting of messages to non-mobile units,such as those used in a distributed advertising system. For example,billboards for lotteries can be programmed to automatically display thejackpot amount. This amount can be sent across cellular networks, withthe calls being made through platform 224.

FIG. 10 is a flow diagram of a call made to a mobile unit according tothe teachings of the present invention. FIG. 10, along with FIG. 11 tobe discussed below, describe the operation of the fraud managementsystem 287 and the protocol handshake mentioned above. Without asuccessful handshake, a call cannot be connected either to or from aremote unit.

As shown in FIG. 10, a call to a mobile unit is first made by placing acall to the platform at block 318. This call is, for a example, a 1-800call, thereby reducing costs to those calling the platform. At block 320the platform requests a mobile unit I.D. for the mobile unit to becalled. This mobile unit I.D., for example, could be a truckidentification number for mobile units placed on trucks. If no mobileunit I.D. number is received or the mobile unit I.D. is not proper, thendecision block 322 returns the flow to block 320. If the mobile unitI.D. is proper, then the platform acquires authorization information atblock 324. Authorization information may be, for example, a credit cardnumber or an authorized code. For example, personal calls made to themobile unit would only be initiated if the caller to the platform gave avalid credit card number. Validation of the credit card number may beaccomplished through credit card validation system 303 of FIG. 8. Forbusiness calls coming from an associated central host, authorization canoccur by entering an authorized code, or by calling in on a specialbusiness line, for example. This authorization occurs at block 326.

If the call is authorized, then the platform calls a mobile unit atblock 328. Platform 224 uses look-up tables 284 of FIG. 8 to associatethe phone number of the remote unit to be called with the mobile unitI.D. Platform 224 then looks up the most recently recorded cellularsystem identification number and switch identification number associatedwith mobile unit 216, such as that provided by the most recent "present"message issued by mobile unit 216 and stored by platform 224. Platform224 then calls the appropriate roamer access port, and dials the phonenumber. Once the call is connected and the platform and mobile unitmodems establish data communication, the mobile unit 216 issues achallenge at block 330. This challenge may be, for example, a randomnumber. If no challenge is received, then the platform 224 disconnectsthe call at block 331. If the platform receives a challenge, then atblock 332 the platform returns a response based on the challengereceived, a key particular to the mobile unit, and an encryptionalgorithm. As noted, the key used in the generation of the response is afunction of the mobile unit and may be generated from a lookup table ofnumbers shared by both mobile unit 216 and platform 224 indexed by theMIN/ESN of mobile unit 216. The encryption algorithm, also known by bothmobile unit 216 and platform 224 can be any appropriate mathematicalalgorithm, and may be modified periodically, as can the lookup table, tomaximize security.

At block 334, the platform determines whether the response is correct byrunning the same encryption algorithm on the challenge and key. If theresponse is not correct, or if no response is received, then the call isdisconnected at block 336. U.S. Pat. No. 5,155,689, issued on Oct. 13,1992, and assigned to By-Word Technologies, Inc., of Dallas, Tex.,discloses a system that connects or disconnects calls based uponinterrogation between two modems in a cellular system. That patent isherein incorporated by reference.

If the response is correct, the call is completed at block 338. At block338, either voice or data or both may be transmitted to or from themobile unit.

For calls from the central host 226 that include voice communications, avoice request is sent to the platform 224 from the central host 226 tocommunicate with a particular mobile unit 216. Any data to be exchangedwith that mobile unit is exchanged before connecting the voicecommunications. For example, data from the central host 226 is deliveredthrough the platform 224 to the mobile unit 216, and any data at mobileunit 216 is delivered at least to platform 224. Next, the platform 224requests that mobile unit 216 to switch to voice, and rings the user ofmobile unit 216. If no answer is received, then no voice connection ismade between mobile unit 216 and central host 226. If an answer isreceived, then platform 224 calls the central host 226 (or any othernumber provided to the platform 224 by the central host) and patches theappropriate connection.

There will be times when calls cannot be delivered to mobile unit 216,for example, when it is out of any cellular system, temporarily out ofcommunication with a cellular system, or powered-down. In such cases, analert will be set at the platform 224, indicating that a call has notbeen completed. Upon receipt of a "present" message, for example, whenthe mobile unit 216 to which the call was intended powers up,re-establishes communication or enters a new cellular system, theplatform 224 can complete the call. If only data is to be transferred,then this data can be sent from the platform 224 to the mobile unit 216.If a voice call had not been completed, then the platform 224 calls thecalling party, for example the dispatcher at a central host, andindicates that a call can be or will automatically be placed to theappropriate mobile unit 216. Furthermore, the user of a mobile unit 216may be provided with a pager/remote ringer, to ensure that he is awareof any voice calls to his mobile unit 216.

FIG. 11 is a flow diagram of a call from a mobile unit 216 according tothe teachings of the present invention. At block 340, the mobile unitwill initiate an outgoing call. The outgoing call can be initiated inany of several ways. The mobile unit 216 can be programmed such thatonly certain pre-programmed numbers can be called. These authorizedphone numbers are stored in remote unit 216 and can be programmedremotely by the central host 226 or platform 224. Thus, a user of aremote unit would only be able to call these pre-programmed numbers andno others. Alternatively, the remote unit could be configured so as toallow personal calls--if eventually authorized--as well aspre-programmed authorized calls. Regardless of what number is to beeventually called, the mobile unit 216 is pre-programmed to first callthe platform at block 342. This call, for example, could be a 1-800number call. Alternatively, arrangements can be made with each cellularsystem to direct all calls from mobile units with particular MIN/ESNs toplatform 224. Each local carrier would recognize these particularMIN/ESNs and route their calls to platform 224. Recognition can occurthrough use of a pre-arranged database, as discussed above. Thehandshake protocol between the mobile unit and the platform is similarto that described in connection with FIG. 10, except that the challengeand response are issued by the platform and mobile unit, respectively.

As shown in FIG. 11, at block 344 the platform issues a challenge aftermodem connection with the mobile unit and receipt of a mobile unit I.D.,such as an MIN. This I.D. provides the platform 224 with knowledge ofwhich mobile unit is calling. If no challenge is received, then themobile unit disconnects the call at block 346. If the challenge isreceived, then the mobile unit returns a response and the platformreceives the response at block 348. The response is generated byexecuting the encryption algorithm on the challenge and the keyparticular to the mobile unit. If the response generated by the mobileunit does not match the desired response generated by the platform, asdetermined at block 350, then the call is disconnected by the platformat block 352. If the response is correct, then the platform receives theultimate number to be called at block 354. If it is determined that thisultimate number to be called is one of the pre-programmed calls at block356, then the call is connected at block 358. Typically, such a callwould be to a user of the central host or a customer. In such a case,voice or data or both can be transmitted. If it is determined at block356 that the ultimate number to be called is not a pre-programmednumber, then an authorization decision is made at block 360. Forexample, block 360 may compromise a credit card authorization step. Ifthere is no authorization for the call, then the call is disconnected atblock 362. If the call is authorized at block 360, for example by entryof a valid credit card number, then the call will be connected at block364. For data transmissions, the data can be stored at platform 224 andtransmitted to central host 226 at various times, as discussed above inconnection with "present" messages.

The system of the present invention provides for several layers of fraudprevention. For calls originating at mobile unit 216, a first layer ofprotection is the ability to restrict outgoing calls to onlypre-programmed calls. Thus, a user of mobile unit 216 may be restrictedfrom calling any unauthorized numbers.

A second layer of fraud prevention is provided by the requirement thatall calls to or from a mobile unit 216 pass through the platform 224.This requirement allows for a myriad of "gatekeeping" functions to beperformed at the platform 224. For example, the platform 224 may connectonly certain authorized calls from the mobile unit 216, and require avalid credit card for all others calls. Likewise, the platform 224 canensure that only authorized calls (such as business calls or credit cardauthorized calls) are directed to the mobile unit 216.

A third layer of protection is provided by the handshake protocol of thepresent invention. With this handshake protocol, fraudulent procurementof the MIN/ESN of the mobile unit 216 will be to no avail withoutknowledge of the handshake protocol. For example, if a call were placeddirectly to the mobile unit 216, through knowledge of its MIN, the callcould not be completed without knowledge of the handshake protocol.

One of the most popular schemes for defrauding cellular users involvesobtaining the MIN/ESN of a particular mobile unit 216, and then cloninga phone with the same MIN/ESN. Such a cloned phone can then be used inmost any cellular system, with the cellular usage charges being billedto the original mobile unit 216 as roamer charges. The present inventionfoils this variety of fraud by requiring that any call using theparticular MIN/ESN of mobile unit 216 be directed through the platform224. As discussed above, this requirement can be accomplished by makingarrangements with the local cellular carriers to trap calls havingparticular MIN/ESNs and route them to the platform 224, or alternativelyforcing all mobile units to only call the platform. The platform 224then requires successful protocol handshaking to connect the call.

Each mobile unit 216 may be equipped with a unique handshake protocol,and the platform 224 would maintain a data base that associated eachmobile unit 216 with its unique handshake protocol. Alternatively, alibrary of handshake protocols can be maintained, with each mobile unit216 assigned one of the handshake protocols from that library. Theplatform 224 would then keep a record of which protocol of the libraryis assigned to a particular mobile unit 216, and perform handshakeprotocols accordingly.

The handshake protocol described herein provides an excellent means ofpreventing cellular fraud. It should be understood, however, that mobileunit-cellular system-telecommunications platform architecture of thepresent invention provides technical advantages even without the fraudprevention technique. For example, the ability to gather information onthe cellular system location of the mobile units 216 allows forefficient call delivery to these mobile units.

Throughout this description of the invention, the central host 226, theplatform 224, the clearinghouse 222, and the cellular system 212 havebeen discussed as separate elements. It should be understood that eachof these components are logical components, and they may be combinedwithout physical separation. For example, the functions of the platform224 and the central host 226 may be accomplished at a single site.Likewise, the functions of the platform 224 or clearinghouse 222 may beperformed at the local cellular system, for example, at the MTSO.

The present invention has been discussed in connection with cellularsystems. It should be understood that it may also be used in connectionwith satellite telecommunications systems. For example, the transmissiontowers 218 and MTSO 220 of FIG. 5 may be replaced with, or used inconjunction with, a satellite telecommunications system. Furthermore,transmissions to and from the mobile unit 216 may be across variouschannels, such as separate data and voice channels, for example forpacket data communications.

FIG. 12 is a block diagram of the central host 226 constructed accordingto the teachings of the present invention. As shown in FIG. 12, acentral host includes a processor 366 coupled to memory 368. Datatransmitted to and received from mobile units is transmitted throughmodem 370 to and from processor 366. Such data may be stored in memory368 and displayed on display 372. Furthermore, various data, such asdata to be transmitted to remote units, is input through userinput/output 374. Data which may be input through user input/output 374,for example, may include the text data to be transmitted to a particularremote unit. Such text data could include particular messages, such aschanges in delivery schedules, weather conditions, or the like. Suchdata is displayed on display 268 of remote unit 216, a shown in FIG. 7.Voice communications between a central host and remote units may be madethrough voice phone 376. Throughout this description in drawings,separate communications have been shown for data and voice, with thedata passing through a modem. It should be understood that a singletelecommunications line may be used to provide both voice and datawithout departing from the intended scope of the present invention.

In operation of central host 226 of FIG. 12, data and messages receivedfrom remote units may be displayed on display 372 and output, forexample in hard copy form, through user input/output 374. For example, amap with location identification of each remote unit associated with thecentral host is displayed on display 372. In this way, the central host226 can keep track of the location and progress of remote units and forexample, vehicles associated with the mobile units. The processor 366runs software which allows automated sending of data to particularremote units. This data can be automatically generated by processor 366or input through user input/output 374. Central host can also receiveraw location information, that can then be processed in processor 366 togenerate latitude and longitude coordinates.

Processor 366 may also, by tracking the locations of mobile units, basedon longitude and latitude and road map information, determine how manymiles each mobile unit travels within a particular state. From thisinformation, fleet mileage reports can be generated, for example fortrucking companies. These fleet mileage reports can be used to determinethe distance traveled and amount of fuel used in various states, whichallows for accurate reporting for both fuel and road usage taxes.Furthermore, knowledge of the location of vehicles at particular times,for example from "present" messages or geographic location data, allowsfor calculation of estimated times of arrivals by dispatchers at centralhosts. For example, knowledge that a truck is in Dallas, Tex. onThursday night allows for an estimate of arrival time in Mobile, Ala.

There have been described certain embodiments of the invention that arecapable of data messaging in a communications network. While theseembodiments have been described and disclosed, other changes,substitutions, or alterations can be made without departing from thespirit and scope of the invention, as described in the appended claims.

What is claimed is:
 1. A system for communicating location or statusinformation of a mobile item to be monitored using a cellular telephonenetwork, comprising:a messaging unit coupled to the mobile item, themessaging unit having a cellular transceiver coupled to the cellulartelephone network, the messaging unit operable to alter an identifier ofthe cellular transceiver to reflect the location or status informationof the mobile item and to transmit the altered identifier of thecellular transceiver; and a platform coupled to the cellular telephonenetwork and operable to recognize a received altered identifiertransmitted by the messaging unit to obtain the location or statusinformation of the mobile item.
 2. The system of claim 1, wherein theplatform stores location or status information represented by thealtered identifier.
 3. The system of claim 2, comprising a host coupledto the platform and operable to access the location or statusinformation stored by the platform.
 4. The system of claim 1, comprisinga switch coupled to the cellular telephone network and operable torecognize the altered identifier, and upon recognition, route thealtered identifier to the platform.
 5. The system of claim 1, whereinthe messaging unit is attached to a trucking trailer located within aservice area of the cellular telephone network.
 6. The system of claim1, wherein the altered identifier coveys the location or statusinformation on a reporting event.
 7. The system of claim 1, wherein theplatform is operable to translate the altered identifier into thelocation or status information on a reporting event and to store thelocation or status information on the reporting event.
 8. An apparatusfor communicating location or status information of a mobile item to bemonitored using a cellular telephone network, comprising:a messagingunit coupled to the mobile item, the messaging unit having a cellulartransceiver coupled to the cellular telephone network, the messagingunit operable to alter an identifier of the cellular transceiver toreflect the location or status information of the mobile item; andwherein the cellular transceiver transmits the altered identifier to aremote location that recognizes the altered identifier to obtain thelocation or status information of the mobile item.
 9. The apparatus ofclaim 8, comprising a sensor to generate the location or statusinformation of the mobile item.
 10. The apparatus of claim 9, whereinthe sensor comprises a positioning system.
 11. The apparatus of claim 8,wherein the altered identifier comprises a mobile identification numberof the cellular transceiver.
 12. The apparatus of claim 8, wherein thealtered identifier comprises an electronic serial number of the cellulartransceiver.
 13. The apparatus of claim 8, wherein the cellulartransceiver initiates transmission of the altered identifier by dialinga telephone number.
 14. The apparatus of claim 8, wherein the cellulartransceiver initiates transmission of the altered identifier by issuinga feature request.
 15. The apparatus of claim 8, wherein the cellulartransceiver initiates transmission of the altered identifier duringpre-call validation communication.
 16. A method for communicating statusor location information of a mobile item to be monitored using acellular telephone network, comprising:receiving the status or locationinformation of the mobile item at a messaging unit; altering, by themessaging unit, an identifier of a cellular transceiver to reflect thestatus or location information of the mobile item; transmitting thealtered identifier of the cellular transceiver using the cellulartelephone network; and receiving the altered identifier at a remotelocation, the remote location operable to recognize the alteredidentifier to obtain the status or location information of the mobileitem.
 17. The method of claim 16, comprising the step of receiving thealtered identifier at a platform disposed at the remote location. 18.The method of claim 16, wherein the status or location information isgenerated in response to a time-out signal from a real-time clock. 19.The method of claim 16, wherein the status or location informationcomprises a sensor signal beyond predetermined limits.
 20. The method ofclaim 16, wherein the status or location information is generated inresponse to comprises a request to initiate communication with themobile item.
 21. The method of claim 16, wherein the altered identifieris a mobile identification number of the cellular transceiver.
 22. Themethod of claim 16, wherein the altered identifier is an electronicserial number of the cellular transceiver.
 23. The method of claim 16,wherein the step of transmitting the altered identifier is initiated bydialing a telephone number.
 24. The method of claim 16, wherein the stepof transmitting the altered identifier is initiated by issuing a featurerequest.
 25. The method of claim 16, wherein the step of transmittingthe altered identifier is initiated during pre-call validationcommunication.
 26. The method of claim 17, comprising the followingsteps performed at the remote location:translating the alteredidentifier to retrieve the status or location information; and storingthe status or location information.